Internal combustion engines may use lubricating oil for many purposes including for example, lubricating moving parts, actuating cam phasers, and controlling switching valve lifters for valve stepping and cylinder deactivation. Cam phasers and cylinder deactivation devices generally require a higher oil pressure for actuation during engine operation than the moving parts of the engine require for proper lubrication. Switching lifters generally require high oil pressure for high lift operation and a lower oil pressure for low lift operation.
Since engines having cam phasers or cylinder deactivation devices generally require higher than normal oil pressure for their operation, while other components which do not require high pressure lubrication, such as a valve train components, can be over lubricated. Since valve trains commonly require a relatively low oil pressure to provide adequate lubrication to prevent engine wear, a method of reducing oil pressure to an engine's valve train is desired to reduce overall oil flow and increase engine efficiency.